Liquid-liquid extraction of viral particles with ionic liquids

While ionic liquids (ILs) are already employed for the extraction of a variety of biomolecules from aqueous systems, to date their use for extraction of viral particles has been rarely investigated. Since current methods used for extraction of viral particles are very time consuming, laborious and require specialized equipment or have very low recoveries, the aim of this proof-of-principle was to investigate ILs as a possible alternative for the extraction of whole virus particles. In this study eleven ILs were evaluated with plaque assay and qPCR to determine whether they possess adequate extraction properties. From the first screening we were able to identify at least four liquids with good extraction properties of 2-4 log units. The most promising liquid, [C(4)C(1)Pyr] [NTf2], led to a reduction of > 4 log units of virus P100 and > 3 log units for PRD1. This IL was further evaluated in detail by investigating extraction stability over various pH ranges and salt-concentrations and in the presence of naturally occurring contaminants. This investigation revealed pH-dependency and variable extraction efficiency factors, whereby the best results were observed at the neutral pH of 7.5. In addition to the viral genomic quantity in the aqueous phase, the presence of infectious viruses was also determined. In conclusion, this proof of principle identified some ILs with good virus extraction characteristic and demonstrates a promising single step preparation treatment for aqueous samples.